1. Field
Embodiments of the invention relate to the field of audio speakers; and more specifically, to an audio speaker that uses a moving magnetic piston as the sound producing element.
2. Background
Audio speakers use electrical signals to produce air pressure waves which are perceived as sounds. Many audio speakers use a diaphragm that is movably suspended in a frame. The diaphragm is coupled to a voice coil that is suspended in a magnetic field. The electrical signals representing the sound flow through the voice coil and interact with the magnetic field. This causes the voice coil and the coupled diaphragm to oscillate in response to the electrical signal. The oscillation of the diaphragm produces air pressure waves.
It is necessary for the audio speakers to displace a volume of air to produce sound pressure waves that are perceptible to a listener. A speaker diaphragm is limited in the distance it can move, and this limit become smaller as the speaker is reduced in size. This limits the volume of sound that can be produced by a small speaker, particularly in lower frequency range.
It would be desirable to provide an audio speaker that can displace a larger volume of air from a more compact structure suitable for use in portable devices.